How does instinct work?

Instinct is what an animal knows or does without having to learn it, i.e through genetics. All animals, including humans, are partly driven by
instinct.

For example a spider does not learn how to build it's web, and a human doesn't learn to raise it's eyebrows when it meets someone he/she never met
before. These are behavior related traits that express themselves automatically with no conscious decisions.

However I'm having a hard time trying to understand how genes can code a behaviour.

I recently saw a short film about a certain species of ant that builds it's nest on the bark of a small tree. This species has also developped a very
interesting way of catching prey, instead of foraging the forest floor for insects the worker ants simply wait in line along the border of a large
leaf and wait for an airborne insect to land on the edge of the leaf (that's where a flying insect would usually land, not in the middle). As soon as
it lands the insect is seized and cut to pieces before being transported back to the nest.

First of all, I assume the colony begins when a lone fertile queen chooses a tree and digs a small hole in the bark and begins to lay eggs. How do the
workers "know" how to build the nest? (which is made of cardboard-like paste, similar to wasp nests)

How did the "trap" hunting behavior evolve? it must have appeared in the first place to be selected, but how?

When the nest is attacked by army ants, the workers throw the eggs, larvae and puppae down to the forest floor to distract them, saving the colony.
How did this "sacrificial" behavior evolve?

I presume there are genes that control behavior, and after these mutated the ants developped whatever new strategy, and if it was beneficial it spread
to the rest of the population. But it is quite hard to understand how a gene can define a behavior

Of course this can be applied to any animal I just took these ants as an example.

OK. The first thing to note is that behaviour is the result of neurochemistry, hormones, electrical activity etc.

By biasing the action of these processes, genes can alter behaviour. As all these biological actions are based in genetics (ABE: not to ignore the
effects of environment and experience though, but even these rely on genetically derived systems).

A good one I had to explain a while back, was how rabbits have an instinct to fear poop from carnivores. There is a study that shows how rabbits
raised away from the natural environment show avoidant behaviour of carnivore poop (e.g., fox), but not of herbivore poop (e.g., sheep).

Obviously it couldn't be a learned behaviour, as the rabbits had never seen a fox or sheep. So, what is happening here is that the olfactory system
is sensitized to certain chemicals in carnivore poop. When these are picked up, the FFFS (fight, freeze, and flight system) is activated, and
avoidant/vigilant behaviour results.

Likewise, a human baby is hard-wired to certain emotional behaviours (i.e. disgust responses to certain tastes), and so the rabbit is hard-wired to
avoid/fear the smell of carnivore poop.

As long as these behaviours stay adaptive, the genes underlying the behaviour will be maintained within the population. And I'm sure for rabbits in
natural environments, it will.

More complex behaviours, such as nest building, will be developed and maintained through the same process. These behaviours are essentially mediated
by hormones and chemicals, which are set in place through genetics.

Thus, one study shows how one single gene mediated sexual behaviour in a fly:

Courting behaviour 'in the genes'

A single gene changed the flies' sexual behaviour

Men who are no good at wooing the ladies may be able to blame their genes, after researchers have made a discovery in the humble fruit fly.
Manipulation of a single gene in male fruit flies made them less adept at courting female mates, a US and an Austrian team have both found.

However, it would be remiss to think behaviours are the result of single genes. There are likely multiple interacting genes, regulators of genes, and
developing hormones underlying many behaviours.

For example, take away the gonads of a male rat at birth, and it will show female sexual behaviours when adult (i.e. Lordosis) if the appropriate
hormones are available. Conversely, female rats who have been masculinised will not show lordosis even if hormones are made available, and feminised
male rats won't show normal male behaviour if testosterone is made available. Thus, hormones control sexual behaviour, but are also involved in the
development of the neural basis of sexual behaviour. Much of this is mediated by activity in the hypothalamus (it even shows sexually dimorphic
structure). Similarly, the neocortex is altered by sexual hormones.

Therefore, hormones are also important as motivators of many behaviours (homeostasis). And the systems underlying hormonal activity are basically set
in place by genetics.

Originally posted by DarkSide
Animals are amazing pieces of machinery after all

And so are we. A few years ago I saw a show about dog behavior. I was struck at how much of their seemingly thoughtful behavior is actually innate
and common among all breeds, such as welcome you home by licking your mouth. As the master/provider, your dog is asking you for what you've brought
back to the family.

Makes you wonder how much of our own behavior is hardwired. Take a look at this video of John Denver using Indian sign language, and how it was used
as a form of communication among tribes that spoke different languages. We could meet people from any part of the world and, because we're all
human, we could communicate with universal gestures.

Some are turned on or off by chemicals present in the organism's external environment, which could be ingested, inhaled, absorbed through the skin or
injected by other organisms.

Others are turned on or off by chemicals produced by the organism in response to environmental cues -- chemicals produced when the sun rises, or the
tide is low, or a predator's cry echoes through the night. The production of these chemicals is in turn coded for by other genes, which turn on and
off in response to sensory cues.

When turned on (or off), all the gene does is make (or stop making) proteins in cells in certain parts of the organism. But the presence (or absence)
of these proteins causes the organism to do certain things, which then causes other proteins to be produced (or their production to cease), which in
turn makes the organism do other things. And in that way a whole chain of behaviours, a more or less complex behaviour pattern can emerge.

I've always figured that if you take two infant humans (male and female) who have never seen the act of procreation, and put them on an island cut
off from all other human contact (of course they would somehow get food), they would eventually grow into puberty and just "Know" how to procreate.
This is not a learned behavior, but an instinct that we are all born with.

Animals seem to automatically know how to procreate without being "taught" this behavior.

I sometimes wonder if early humans understood what it meant when they "got the sexual urge". Were they conscious of the fact that the act of having
sex would lead to offspring? Or was the urge just an instinctual behavior that "accidentally" led to pregnancy. I really doubt a dog consciously
"knows" having sex will lead to puppies -- sex is purely an instinctual behavior.

what do you guys think of the theory of morphogenic fields and or psychoenergetics and how would these relate to genetics and behavior. here is a
link to some data at least hinting that they might be real.

i don't really know how but i think there is a paranormal side to it, i mean i heard that during the Oklahoma city bombings almost all 17 people that
working in that building didn't go to work that day, and during 9/11 the planes were more than half empty and some of the people that were supposed
to be on the planes said that they felt very ill the day or days before their flight.

This content community relies on user-generated content from our member contributors. The opinions of our members are not those of site ownership who maintains strict editorial agnosticism and simply provides a collaborative venue for free expression.